Oxidation Of Methyl Tert-butyl Ether Research Articles

O 3/H 2O 2 treatment of methyl- tert-butyl ether (MTBE) in contaminated waters

The kinetics and efficiency of oxidation of methyl- tert-butyl ether (MTBE) in contaminated water employing O 3/H 2O 2 advanced oxidation process is presented in this paper. Kinetic simulation is based on the model mechanism published in literature (Staehelin and Hoigne, Environ. Sci. Technol. 16 (1982) 676; Glaze and Kang, Ind. Eng. Chem. Res. 26 (1989) 1573) indicates that the oxidation of MTBE is primarily induced by the hydroxyl radical. The degradation of MTBE can be described by a pseudo-first-order kinetics in two phases. The first-phase covers MTBE concentrations greater than 10 mg L −1 and the second-phase covers MTBE concentrations below 10 mg L −1. The rate of oxidation of MTBE (at least in the first-phase) is limited by ozone mass transfer and increases with increasing ozone gas flow rate. The pseudo-first-order reaction rate constant varies from 2.0×10 −3 to 5.4×10 −3 s −1 over the range of ozone gas flow rate employed in this investigation. An efficiency index is defined and its value for the oxidation of MTBE in different water is provided. The data provided show that remediation of MTBE-contaminated groundwater by O 3/H 2O 2 process is more efficient and less costly than by the UV/H 2O 2 process.

Methyl tert-Butyl Ether Catalytic Oxidation over Pt/Rh and Pd Monolithic Exhaust Catalysts: Intrinsic Kinetic Studies in a Spinning Basket Flow Reactor

Kinetic studies of methyl tert-butyl ether (MTBE) oxidation over Pt/Rh and Pd monolithic automotive catalysts were performed in a spinning basket flow reactor under atmospheric pressure. The reaction temperature was varied between 350 and 550 K, while MTBE concentration ranged from 10 to 500 ppm and oxygen concentration from 103 to 105 ppm. Various kinetic models have been tested in the analysis of the experimental data obtained in this work. The model that takes into account the surface reaction between dissociatively adsorbed reactants was found to yield the most successful fit and to be valid for both catalysts. According to this model, the activation energy of MTBE oxidation over Pt/Rh and Pd is estimated as 38 200 ± 110 J mol-1.

Rate Constants Deduced by Ab-Initio Calculations for Decomposition Reactions of CH3OCH2, C4H9OCH2 and C4H8OCH3 Radicals

The importance of thermal decompositions during the oxidation of methyl tertbutyl ether (MTBE) has motivated a theoretical investigation of reactions: C

Experimental and modeling study of the gas-phase oxidation of methyl and ethyl tertiary butyl ethers

The gas-phase oxidation of methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) has been experimentally studied using a jet-stirred reactor between 750 and 1150 K (pressure of 10 atm, equivalence ratios from 0.5 to 2 with an important dilution in nitrogen). These experiments have been modeled using a kinetic mechanism automatically generated by EXGAS, the system developed in Nancy. The modeling of the oxidation of several mixtures of these ethers with n-heptane has also been performed in an extended temperature range, between 580 and 1100 K, covering the regions of cool flames and a negative temperature coefficient. The agreement between the computed and the experimental values is mostly good, both for conversions and for the distribution of major products, except for the lowest temperatures, where catalytic effects should be taken into account. The decrease of reactivity due to the addition of MTBE or ETBE to n-heptane at low temperatures is well predicted by the model.

Biodegradation of the gasoline oxygenates methyl tert-butyl ether, ethyl tert-butyl ether, and tert-amyl methyl ether by propane-oxidizing bacteria.

Several propane-oxidizing bacteria were tested for their ability to degrade gasoline oxygenates, including methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME). Both a laboratory strain and natural isolates were able to degrade each compound after growth on propane. When propane-grown strain ENV425 was incubated with 20 mg of uniformly labeled [14C]MTBE per liter, the strain converted > 60% of the added MTBE to 14CO2 in < 30 h. The initial oxidation of MTBE and ETBE resulted in the production of nearly stoichiometric amounts of tert-butyl alcohol (TBA), while the initial oxidation of TAME resulted in the production of tert-amyl alcohol. The methoxy methyl group of MTBE was oxidized to formaldehyde and ultimately to CO2. TBA was further oxidized to 2-methyl-2-hydroxy-1-propanol and then 2-hydroxy isobutyric acid; however, neither of these degradation products was an effective growth substrate for the propane oxidizers. Analysis of cell extracts of ENV425 and experiments with enzyme inhibitors implicated a soluble P-450 enzyme in the oxidation of both MTBE and TBA. MTBE was oxidized to TBA by camphor-grown Pseudomonas putida CAM, which produces the well-characterized P-450cam, but not by Rhodococcus rhodochrous 116, which produces two P-450 enzymes. Rates of MTBE degradation by propane-oxidizing strains ranged from 3.9 to 9.2 nmol/min/mg of cell protein at 28 degrees C, whereas TBA was oxidized at a rate of only 1.8 to 2.4 nmol/min/mg of cell protein at the same temperature.

Metabolism of Diethyl Ether and Cometabolism of Methyl tert-Butyl Ether by a Filamentous Fungus, a Graphium sp

In this study, evidence for two novel metabolic processes catalyzed by a filamentous fungus, Graphium sp. strain ATCC 58400, is presented. First, our results indicate that this Graphium sp. can utilize the widely used solvent diethyl ether (DEE) as the sole source of carbon and energy for growth. The kinetics of biomass accumulation and DEE consumption closely followed each other, and the molar growth yield on DEE was indistinguishable from that with n-butane. n-Butane-grown mycelia also immediately oxidized DEE without the extracellular accumulation of organic oxidation products. This suggests a common pathway for the oxidation of both compounds. Acetylene, ethylene, and other unsaturated gaseous hydrocarbons completely inhibited the growth of this Graphium sp. on DEE and DEE oxidation by n-butane-grown mycelia. Second, our results indicate that gaseous n-alkane-grown Graphium mycelia can cometabolically degrade the gasoline oxygenate methyl tert-butyl ether (MTBE). The degradation of MTBE was also completely inhibited by acetylene, ethylene, and other unsaturated hydrocarbons and was strongly influenced by n-butane. Two products of MTBE degradation, tert-butyl formate (TBF) and tert-butyl alcohol (TBA), were detected. The kinetics of product formation suggest that TBF production temporally precedes TBA accumulation and that TBF is hydrolyzed both biotically and abiotically to yield TBA. Extracellular accumulation of TBA accounted for only a maximum of 25% of the total MTBE consumed. Our results suggest that both DEE oxidation and MTBE oxidation are initiated by cytochrome P-450-catalyzed reactions which lead to scission of the ether bonds in these compounds. Our findings also suggest a potential role for gaseous n-alkane-oxidizing fungi in the remediation of MTBE contamination.

Kinetics and Modeling of Mixture Effects during Complete Catalytic Oxidation of Benzene and Methyl tert-Butyl Ether

The performance of a catalytic incinerator depends on the nature of the compounds being oxidized and cannot be predicted simply by knowing the performance of the incinerator with pure-component model compounds. Considering the importance of “mixture effects”, an attempt was made to develop a combined model to predict the conversion when benzene and methyl tert-butyl ether (MTBE) are simultaneously oxidized. Complete catalytic oxidation of benzene and MTBE, singly and in mixtures, was investigated over a platinum catalyst. No inhibition effects were seen with benzene, but MTBE conversion was distinctly inhibited by benzene. A Mars−van Krevelen rate model was used to explain the results. Model parameters were obtained from pure-component experiments and then incorporated into a multicomponent model without any adjustment or additional rate parameters. The multicomponent model was able to predict the conversion of benzene and MTBE oxidation in the binary mixture using the pure-component data without adjustable parameters.

Oxidation of Methyl tert-Butyl Ether (MTBE) and Ethyl tert-Butyl Ether (ETBE) by Ozone and Combined Ozone/Hydrogen Peroxide

Abstract The aim of this work was to study the reaction of ozone and combined ozone/hydrogen peroxide on oxygenated additives such as methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) in dilute aqueous solution using controlled experimental conditions. Experiments conducted in a semi-continuous reactor with MTBE and ETBE in combination (initial concentration: 2 mmol/L of each) showed that ETBE was better eliminated than MTBE with both ozone and combined O3/H2O2. Batch experiments led to the determination of the ratio of the kinetic constants for the reaction of OH°-radical with MTBE and ETBE [kOH°/ETBE/kOH°/MTBE = 1.7). Tert-butyl formate and tert-butyl acetate were identified as the ozonation byproducts of MTBE and ETBE, respectively, while tert-butyl alcohol was found to be produced during the ozonation of both compounds.